Effects of Samarium Oxide Addition on the Phase Composition, Microstructure, and Electrical Resistivity of Aluminum Nitride Ceramics

The phase composition, microstructure, and electrical resistivity of hot‐pressed AlN ceramics with 0–4.8 wt% Sm 2 O 3 additive were investigated. The phase composition was approximately consistent with that estimated from the Sm 2 O 3 –Al 2 O 3 phase diagram using the amount of added Sm 2 O 3 and oxygen content of the AlN raw material. When sintered at more than 1800°C, the AlN ceramics with 1.0–2.9 wt% Sm 2 O 3 additive contained an Sm‐β‐alumina phase wetting the grain boundaries, and their electrical resistivity considerably decreased to 10 10 –10 12 Ω·cm. This resistivity decrease was caused by the continuity of the Sm‐β‐alumina phase with a resistivity lower than that of bulk AlN.